A Coupled Wellbore-Reservoir Simulator Utilizing Measured Wellhead Conditions

Abstract

Modeling a geothermal system requires simulating the behavior of a reservoir and the flow in production wells, which is usually done individually. The main objective in this study is to develop a coupled wellbore-reservoir simulator to allow for more integrated modeling and to use wellhead conditions to a greater extent than has been done so far by defining them as main inputs to the coupled model. The program TOUGH2 is used to simulate the behavior of a reservoir while a new model, FloWell, is designed to simulate two phase flow in a wellbore. Furthermore, the model design in FloWell and in TOUGH2 is improved by calibration with the parameter estimation program iTOUGH2 during the coupling procedure. Emphasis is placed on adjusting the permeability distribution in a reservoir, productivity indices of wells and parameters in void fraction correlations for there are some great uncertainties involved in the assessment of these parameters, which have led to disagreement among investigators. This paper discusses in detail the methodology behind the coupling procedure and raises questions like: What can be accomplished with this coupled model? What are the limitations of the coupled model? The proposed coupling procedure in this paper is put to a test by examining the Reykjanes geothermal field located at the southwestern corner of Iceland and results analyzed.